[vlc-devel] [PATCH] videotoolbox: set kCVPixelBufferBytesPerRowAlignmentKey to 16

[Zhao Zhili]

Hi Jean-Baptiste，

On Mon, Jul 10, 2017 at 1:39 AM, Jean-Baptiste Kempf <jb at videolan.org>
wrote:

> Why?
>
> I'm sorry, but this means a bit more justification, in the commit log, and
> probably in the code.
>
>
1. Set  kCVPixelBufferBytesPerRowAlignmentKey to 16 makes memory usage
smaller on iOS devices.
2. I didn't find any side effect of this setting.
3. I asked on IRC and cannot figure out why set align to i_video_width * 2.



>
> On Sun, 9 Jul 2017, at 03:19, Zhao Zhili wrote:
>
>
> ---
>  modules/codec/videotoolbox.m | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/modules/codec/videotoolbox.m b/modules/codec/videotoolbox.m
> index 7806bd7843..9443bbe256 100644
> --- a/modules/codec/videotoolbox.m
> +++ b/modules/codec/videotoolbox.m
> @@ -692,8 +692,7 @@ static int StartVideoToolbox(decoder_t *p_dec)
>      cfdict_set_int32(p_sys->destinationPixelBufferAttributes,
>                       kCVPixelBufferHeightKey, i_video_height);
>      cfdict_set_int32(p_sys->destinationPixelBufferAttributes,
> -                     kCVPixelBufferBytesPerRowAlignmentKey,
> -                     i_video_width * 2);
> +                     kCVPixelBufferBytesPerRowAlignmentKey, 16);
>
>      /* setup decoder callback record */
>      VTDecompressionOutputCallbackRecord decoderCallbackRecord;
> --
> 2.11.0 (Apple Git-81)
>
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